Fermi Large Area Telescope Fourth Source Catalog Data Release 2

TL;DR

This paper presents an updated gamma-ray source catalog from the Fermi-LAT telescope, incorporating ten years of data, new source identifications, and revised spectral and temporal information.

Contribution

It provides an incremental update to the fourth Fermi-LAT source catalog with new sources, associations, and refined analysis methods based on a decade of data.

Findings

723 new gamma-ray sources identified

53 sources newly associated with counterparts

Light curves updated with 1-year intervals

Abstract

We present an incremental version (4FGL-DR2, for Data Release 2) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first ten years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods as the 4FGL catalog did for eight years of data. The spectral parameters, spectral energy distributions and associations are updated for all sources. Light curves are rebuilt for all sources with 1-year intervals (not 2-month intervals). Among the 5064 4FGL sources, 120 are formally below the detection threshold over 10 years (but are kept in the list), while 53 are newly associated and four associations were withdrawn. We report 723 new sources, mostly just above the detection threshold, among which two are considered identified and 341 have a plausible counterpart at other wavelengths.